Composite material



Patented Apr. 7, 1942 COMPOSITE MATERIAL Edward W. Rugeley, TheophilusA. Feild, Jr., and John F. Conlon, Charleston, w. va., assignors toCarbide and Carbon Chemicals Corporation,

a corporation of New York No Drawing. Application December 6, 1938,

Serial No. 244,176

17 Claims.

This invention relates to composite materials, and it is directedparticularly to composite textiles having marked properties of creaseresistance, increased strength and retention of shape.

In the manufacture of many kinds of articles which are composedessentially of separate fibers, such as fiber mats, fabrics and thelike, it is often desirable to hold the fibers in the shape or formdesired by means of-some binding or stillening agent. Ordinarily thismay be accomplished by impregnating the cloth, felt or fiber mat with anadhesive, preferably dissolved in a sufi'icient amount of a solvent toproduce a solution which will penetrate between the fibers. Such atreatment, however, tends to fill the interstices of the fabric or mat,reducing its porosity and altering its appearance and properties to anobjectionable degree for many uses. These disadvantages have beenovercome to a certain extent by interweaving threads of celluloseacetate in the fabric and fusing the cellulose acetate to the otherfibers. However, the fusion point of cellulose acetate is high enough tomake resetting or reshaping operations diificult, as well as hard on thefabric, unless solvents for the cellulose acetate are used. The solventsnormally employed, such as' acetone, are objectionable in that theyinvolve'a fire hazard in commercial use. In other types of articles suchas mops, dusters, scouring cloths and the like, binding the materialwith cellulose acetate is impractical where resistance to water, acids,and alkalies is necessary.

This invention provides composite fibrous articles of the classesdescribed having certain advantages and properties which adapt them fora wide variety of uses and which are not found in the ordinary compositematerials. For example, the fabrics of the invention which are suitablefor the manufacture of clothing are characterized by a resistance tocreasing or wilting, under ordinary conditions of use, that isconsiderably greater than that of standard materials, and they may belaundered many times and subjected to such reshaping operations asironing, calendering and pressing, as encountered in the-usual laundry,each time to emerge properly shaped or reshaped without the necessity ofemploying exits original form after being pressed out of shape forfairly long periods of time. For other types of articles such as mops,dusters, asbestos pads, and scouring mats containing metal fibers, thisinvention provides materials which do not easily leave small pieces, orlint, upon the surfaces with which they come in contact. In the case ofmattresses, pillows, quilts or stuffed upholstery, this inventionprovides a stufling which has increased resistance to packing orseparation into uneven and relatively hard lumps, yet retains all of thenatural resiliency and softness of new stufling. Textile threads oryarns made in accordance with this invention have, in general, a highwet tensile strength by comparison with other fibers,

, and they have increased resistance to deterioraas distinct from acomposite yarn.

cessive temperatures or additional binding or stiffening agents orsolvents therefor. In the case of pile fabrics such as velvet and theheavier materials used for rugs and upholstery, made in accordance withthis invention, the material itself is not only unusually resistant tocreasing, but the pile is not easily crushed and will resume tion byacids, alkalies, and bacterial or fungal attack.

The materials of this invention consist essentially of compositefabrics, or of materials which may be woven, knitted or otherwisefashioned from composite yarns or threads. Where the composite yarn isemployed, it may consist of one or more fibers of any of the well knowntextiles, such as wool, silk, cotton, linen and rayon, with which havebeen combined fibers or filaments of a vinyl resin having certaincharacteristics. In the case of woven fabrics or any materials made froma plurality of yarns, the desired properties of crease resistance,increased strength and the like may be obtained by incorporating thevinyl resin in the form of one or more of the individual yarns of thefabric, For example, a cloth may be woven with alternate threads ofvinyl resin yarn, orin other combinations. For ribbons, a satisfactorymaterial may be obtained by calendering parallel alternate threads ofvinyl resin and another textile, the vinyl resin threads fusing to forma cross binder.

Composite yarns composed of continuous filaments may be made by twistingor doubling the vinyl resin fibers with other continuous filaments suchas the cellulose esters, regenerated cellulose, other artificial fibers,spun cotton yarn, or silk. However, the fabrication of composite stapleyarns is the more easily effected, since the staple vinyl resin fibersmay be carded in the proper ratio with whatever other staple fibers aredesired, and the composite yarn spun therefrom in the usual manner.

The vinyl resins from which fibers suitable for use in this inventionmay be made should have average macromolecular weights of at least 7,500and where the fibers must have high strength, the macromolecular weightshould be at least 15,000, while the upper value is limited only by thesolubility of the resins in suitable polymers having excessively lowmolecular weights in order that the average macromolecular weight of theresin will be at least the minimum stated above. This may beaccomplished by various extraction procedures, such as those describedin Patent 1,990,685 to C. 0. Young and S. D. Douglas, or by similarmethods of partial dissolution and precipitation.

Although fibers of any vinyl resins having the macromolecular weightsdescribed above may be used in making the materials of this invention,the strongest and most durable fibers are made from the vinyl esterresins, especially such as are described in Patent 1,935,577 to E. w.Reid,

and these resins may be made by the processes described in that patentor by other means, such as the process described in Patent 2,064,565 toE. W. Reid. 01 these resins, which are known as conjoint polymers ofvinyl halides with vinyl esters of aliphatic acids, the preferred resinsare those which contain from about 50% to about 95% by weight of thehalide in the polymer. The particular composition which is mostdesirable depends upon the nature of the material with which the vinylresin is to be combined, and its intended use, for increasing the vinylhalide in the polymer increases its fusion temperature. In the samemanner, increasing the macromolecular weight of the resin raises itsfusion temperature, so that if a resin is selected which is composedalmost entirely of a vinyl halide, it is desirable that itsmacromolecular weight be relatively low, so that its fusion temperaturewill not be high enough to injure other textile fibers or render shapingoperations dimcult. The most desirable resins of this type are made bythe conjoint polymerization of vinyl chloride with vinyl acetate, andwhere high strength is desired, the vinyl chloride in the polymer shouldbe between about 80% and about 95%, with a macromolecular weight notvery much lowerthan about 15,000.

These conjoint polymers ota vinyl halide and a vinyl ester of analiphatic acidare resistant to water, acids, alkalies, hydrocarbons andalcohols, although they are soluble in ketones, such as acetone, andmost chlorinated hydrocarbons. In addition, they are immune to attack bybacteriar or fungi.

Where the fabric may be exposed to concentrated ultraviolet light or toelevated temperatures for long periods of time, as is the case with someindustrial fabrics, the polyvinyl partial acetal resins may be moresuitable than the vinyl ester polymers. These resins may be consideredas the reaction product of polymerized vinyl alcohol with aninsuificient quantity of aldehyde to acetalize all of the hydroxylgroups or the polyvinyl alcohol. Since two molecular equivalents 01 themonomeric vinyl alcohol, in the polymerized material, will combine withone molecule of aldehyde, the degree to which the aldehyde has beencombined with the polyvinyl alcohol may be indicated directly as percentacetalization. The polyvinyl partial acetal resins which areparticularly suitable for use in this invention are, in general, thosein which the'polyvinyl alcohol has been acetalized, or combined withaldehyde,'from about 33% to about 94%, with an aliphatic aldehyde havingfrom two to six carbon atoms; although the degre of acetalization variesto some extent with the aldehyde employed. The preferred resins arethose in which the polyvinyl alcohol has been acetalized from 88% to 94%with acetaldehyde, from 52% to 92% with propionaldehyde, from 42% to 82%with butyraldehyde, from 35% to 62% with valeraldehyde, or from about33% to 45% with hexaldehyde. Of these, the polyvinyl partial acetalresins acetalized from 42% to 82% with 7 them,

butyraldehyde are especially desirable. The actual degree ofacetalization will also depend upon the desired thermoplasticity of theresin. Increased acetalization, or increase in the molecular weight ofthe aldehyde employed, decreases the softening point of the resin. Thepolyvinyl alcohol may be acetalized with a mixture of aldehydes, ifdesired, providing the total acetalization is within the broad rangegiven. The polyvinyl partial acetal resins described are insoluble inwater, hydrocarbons and ketones, and they are soluble in alcohols and.water-miscible liquids like the glycol monoalkyl ethers. These resins donot have the excellent resistance to water,alkalies and acids that ischaracteristic of theconjoint polymers of vinyl halides with vinylesters of aliphatic acids, and therefore fibers made from them are lessdesirable for incorporation in fabrics which are to'be submerged inwater for very long periods of time, or subjected to many repeatedlaunderings.

The polyvinyl partial acetal resins may be made directly from polyvinylalcohol, or they may be made by the simultaneous hydrolysis andacetalization of a polyvinyl ester, and the method by which theyoriginate is not essential to this invention,

Both the vinyl ester resins and the polyvinyl partial acetal resins maybe spun into filaments by the "dry-spinning process, preferablyemploying acetone as the solvent for the vinyl ester resins and methanolas the solvent for the polyvinyl partial acetal resins, but since theconjoint polymers of a vinyl halide with a vinyl ester of an aliphaticacid are the preferred resins for use in this invention and requirespecial treatment to impart high tensile strength to the fibers madetherefrom, the following description of the preparation of the fibers iswith reference to In general, the vinyl ester resin may be dispersedsatisfactorily in warm dry acetone. By dry acetone is meant thissubstance which contains less than about 0.60% by weight of water. Theconcentration of the vinyl resin in the spinning solution is dependentupon and varies inversely with the-macromolecular weight of the resin,but the resin content ordinarily employed using acetone as the solventis about 25% or less by weight.

The spinning, or filament extrusion, operation may be carried out inequipment customarily employed for so-called dry-spinning of other typesof textile filaments. A bobbin-type thread take -up may be employed, orthe filaments may be given a twist at the point of spinning by employinga cap-type" mechanism. If staple fibers are to be made, the filamentsmay be gathered into a thread and passed directly to the staplingmachine, unless the filaments are to be stretched before being combinedwith other fibers. The filaments or thread delivered from the take-upbobbin may be twisted, or doubled and twisted, to form a yam. Unless aspecial treatment is applied, it is necessary in most cases to permitthe freshly-extruded filaments to age for at least twelve hours beforethe twistin'g and doubling operations are performed, but aging of thefilaments can be advantageously accelerated or replaced by a more brieftreatment with heated water. For example, if the-filaments on thebobbins are immersed in water at 65 C. for a period of 2 to 5 hours, nofurther aging is required.

The next step in the yarn processing is that of stretching. Theimportance of this step is more or less in direct proportion to thestrength desired in the fibers when being carded or combined with othertextiles. An unstretched vinyl resin staple may tend to stretch duringspinning of the staple yarn, whereas the previously stretched fiber doesnot appreciably elongate upon being made into a composite yam. Fusion ofa stretched vinyl resin filament to other textile fibers does notincrease the strength of the material more than will the fusion of anunstretched fiber, since the increase in strength of the compositematerial is largely due to the bind- 30 ing effect of the vinyl resinfilaments. In cases where it is desirable to impart a creping orcrimping effect to the fabric (which has an effect upon the porosity ofthe fabric) the stretching of the yarn is of paramount importance, forit is by heating the finished fabric to about the softening temperatureof the resin, with a consequent release of the strains developed in thestretching operation, that the shrinkage is obtained. The stretchingoperation may be applied equally advantageously to the polyvinyl partialacetal resins as to the vinyl ester resins.

If it is desirable to stretch the yarn, the amount of stretch impartedto the yarn may vary considerably up to about 400%, and in normalprocedure a stretch of about 75% to 180% may be applied. The extent ofthe stretch used is determined by the polymer size (averagemacromolecular weight) of the resin, and by the characteristics desiredin the finished fabric. It is important to conduct this operation whilethe yarn is adequately surface-wetted, and this may be done by immersingthe spools from which the yarn is to be stretched in water which maycontain a wetting agent or surface tension depressant, such as a sodiumsalt of a higher alkyl sulfate, or another of the materials commonlyused for this purpose in textile operations. It may be desirable toapply the stretch in two or more stages. Thus, the yarn may be initiallystretched, say, 90%, and in two subsequent operations given additionalstretching to the extent of or 20% in each stage.

For a period after the yarn has been stretched, it shows a markedtendency to contract. This characteristic may be readily controlled andmodified by a setting treatment, for example, by prolonged aging of theyarn under tension, or by subjecting the yarn under tension tomoderately elevated temperatures, which greatly accelerate the rate ofsetting. After this setting treatment the continuous filament yam may beincorporated directly with other textiles or it may first be stapled andthen carded with other fibers.

The process of producing yarn from the con- 75 Joint polymers of a vinylhalide and a vinyl ester of an aliphatic acid, which is suitable for usein this invention is disclosed in Patent No. 2,161,766, issued June 6,1939, to E. W. Rugeley, T. A. Feild and J. F. Conlon, with which thisapplication contains material in common.

In order to impart the characteristics of crease resistance and creasepermanence to the'finished composite fabric, it is generally necessarythat the filaments of the vinyl resin incorporated into the fabric befused or at least partly fused, thereby bonding the vinyl resin with theother fibers present. Since the vinyl resins described arethermoplastic, the desired shape or crease may be imparted to the fabricat elevated temperatures. When used in conjunction with such fibers ascellulose acetate, it is desirable to select a vinyl resin whosemolecular weight approaches the lower limit specified, and which may atthe same time contain a lower percentage of the vinyl halide in thepolymer, if the conjointly polymerized vinyl ester resin is employed, ora high degree of acetalization if the polyvinyl partial acetal resin isemployed. The reason for this is that where the vinyl resin filamentsare to be fused with other thermoplastic fibers, such as celluloseacetate, it is necessary to employ a vinyl resin of lower softeningpoint than the cellulose acetate, so that the latter will not beadversely affected.

There are many applications of the vinyl resin filaments described. Forexample, vinyl resin staple may be carded with cotton in a ratioempiracally determined for the desired ultimate binding effect. The cardsliver is spun by the standard cotton system and the threads then woveninto a fabric which may be used as an interliner for non-wiltingcollars, cuffs, shirt fronts, and the like. The thermoplastic vinylresin will on each laundering and pressing function as a stiffening andnon-creasing agent for the multiple layer fabric construction. Analternate method consists in preparing a thin felt of vinyl resin stapleand cotton, placing this between the outer fabrics and heating underpressure. The vinyl resin produces a tight bond between the layers. Incases where an especially dull appearance of the material is desired, apigment, such as titanium oxide, in finely-divided form, may beincorporated in the vinyl resin filament by dispersing the pigment inthe vinyl resin solution or dope" from which the filaments are spun.

It is generally recognized that a spun staple fabric consisting eitherof viscose or cellulose acetate staple, although of pleasing appearanceis unsatisfactory with respect to strength, both in the wet and drystate, and is characterized by a tendency toward distortion, andsusceptibility toward creasing. The carding of the vinyl resin staplewith viscose or cellulose acetate staple in a ratio ranging from 10% to20%, the spinning of the thread in the normal fashion, the weaving ofthe fabric and the calendering of the finished fabric yields a productof markedly improved tensile strength, both in the wet and dry states,of good crease resistance, of excellent resistance to distortion, and ofa pleasing full hand" without harshness. Such fabrics serve well asdress goods.

Carding the vinyl resin staple with wool, spinning and weaving thethreads thus formed, followed by a calendering treatment at the end ofthe usual finishing treatment yields a composite fabric that withstandsacid carbonizing. The fabric is of higher strength, which isparticularly desir- 'able in light-weight worsted-construction, that iscrease resistant and tends to retain pressed lines after each pressing,and that is capable of being made up in special novel mottled effects bycross dyeing if desired.

Due to the chemical resistance of the vinyl ester resins described,yarns prepared by carding together vinyl ester resin staple and cottonmay, if desired, be given the usual mercerization treatment for cottonalone, while at the same time the calendered fabrics have increasedstrength, a novel appearance and improved hand." These fabrics, whethermercerized or not, are particularly suitable for the fashioning ofsummer suits.

Since the vinyl ester resins described have much of the chemicalresistance, certain physical properties and non-support of combustion ofglass, they may be combined with glass fiber, either in the form ofcontinuous filaments, or staple fibers of the two materials may becarded together. In the latter case the thread may be spun under theconditions developed for glass fiber staple spinning, whereupon it isgiven a heat treatment so that the resin may partly fuse and act as abinder for the glass filaments. Such binding is highly preferable tothat normally employed, since a higher strength thread results, there isno appreciable loss of strength on wetting, and the effect is permanent,along with chemical resistance and the special physical properties ofthe two fibers. The polyvinyl partial acetal resin filaments maysimilarly be combined with glass fibers, but these resins do not havethe unusual chemical resistance of the vinyl ester resins. In additionto the composite goods mentioned, the vinyl resin fibers may be used assupporting threads for asbestos yarn, the thread if desired beingespecially made up with loops to aid in picking up the asbestos fibers,preferably following by partial fusion. Composite threads or strings ofsilk and vinyl resin fibers may be used for the manufacture of tennisracket strings and like materials, since such threads after bonding thefibers by fusion are very strong and impervious to moisture. Unwovenribbons may be made by calendering parallel threads of natural 'orartificial silk and vinyl resin filaments, since the partial or completefusion of the vinyl resin serves as a cross binder for the othermaterials. Composite threads of artificial silk and vinyl resin fibersmay be used in sewing suit linings, for upon pressing the vinyl resinfibers will lock the stitch to the material. Cotton staple, carded withthe vinyl resin staple described, may be heated to the fusingtemperature of the resin without pressing to form a fluffy stufii'ngwhich maintains its shape well.

Where the vinyl resin fibers have been stretched during theirpreparation, they will shrink to some extent upon being bonded to theother textile fibers, unless the material is supported under tensionwhile the fusion of the vinyl resin fibers takes place. This shrinkagecauses the vinyl resin fibers to become quite crinkled, and so helps tobind all of the fibers together.

Other vinyl resins than the ones described are suitable for use in thisinvention, provided they are'insoluble in water, have averagemacromolecular weights of at least 7,500, and have softening pointssufficiently low so that they may be fused with textiles without injurythereto.

Many special uses and adaptations of the materials of this inventionwill be apparent to those skilled in the art. The procedures by whichthe new materials are made can be varied in many of ill their details,and such modifications are included within the invention as defined bythe appended claims.

We claim:

1. Composite materials comprising fibers'reinbers .mixed with fibers ofa vinyl resin substantially identical with the resin resulting from theconjoint polymerization of a vinyl halide with a vinyl ester of analiphatic acid and containing between about 50% and about 95% by weightof the halide in the polymer, said vinyl resin having an averagemacromolecular weight of at least 7500, said vinyl resin fibers being atleast partially heat-fused with said textile fibers.

4. Composite materials comprising textile fibers combined with fibers ofa vinyl resin substantially identical with the resin resulting from theconjoint polymerization of vinyl chloride with vinyl acetate, whichcontains from about to about by weight of the chloride in the polymerand which has an average macromolecular weight of at least 15,000, saidvinyl resin fibers being at least partiallyfused with said textilefibers.

5. Composite materials comprising staple fibers of a vinyl resinsubstantially identical with the product resulting from the conjointpolymerization of a vinyl halide with a vinyl ester of an aliphatic acidand containing between about 50% and about 95% by weight of the halidein-the polymer, and said vinyl resin having an average macromolecularweight of at least 7,500, said staple fibers being combined with metalfibers;

6. Composite materials comprising staple fibers of a vinyl resinsubstantially identical with the product resulting from the conjointpolymerization of a vinyl halide with a vinyl ester of an aliphatic acidand containing between about 50% and about 95% by weight of the halidein the polymer, said vinyl resin having an average macromolecular weightof at least 15,000, said fibers being at least partially heat-fused withmetal fibers.

7. Heatand light-resistant composite mateof at least 7,500, and beingresistant to ultraviolet light and to elevated temperatures for longperiods of time.

8. Heatand light-resistant composite materials comprising staple fibersof a vinyl resin substantially identical with a polyvinyl partial acetalresin wherein the polyvinyl alcohol has been acetalized with an aldehydefrom the group weight of" at least about 15,000, said vinyl resin fibersbeing at least partially fused to said asbestos fibers.

10. Composite materials comprising asbestos fibers supported by fibersof a water-insoluble vinyl resin having an average macromolecular weightof at least about 15,000, said vinyl resin fibers having been stretchedup to about 400%, said vinyl resin fibers being at least partially fusedto said asbestos fibers.

11. Method of making a stabilized textile fabric which includes yarns ofat least two different types of fibers of textile making length, one ofwhich is awater-insoluble vinyl resin fiber having inherent tackiness onheating and having an average macromolecular weight of at. least 7500;which comprises forming a fabric containing said difierent types offibers and stabilizing said fabric by subjecting it to heat at atemperature at which said synthetic resin fibers become tacky, but belowthe temperature at which the other fibers are damaged, to cause strongand substantially permanent adhesion of said fibers in said textilefabric without rendering the textile nonporous, whereby said fabric ishighly resistant to creasing and wilting and is capable of beingreshaped at temperatures sufiiciently low to prevent injury to thefabric while retaining its natural resiliency and softness.

12. Method of making stabilized textile fabric from at least twodifferent types of textile yarns,

one of which consists of thermoplastic synthetic vinyl resin fibers,said vinyl resin having an average -macromolecular weight of at least7500, which comprises forming a fabric of said difierenttypes of yarnsand stabilizing said fabric by subjecting it to heat at a temperature atwhich said vinyl resin fibers become tacky but below the temperature atwhich the other fibers are damaged, to cause a strong and substantially.permanent adhesion of said fibe'rs in said textile fabric withoutrendering the textile non-porous, whereby said fabric is highlyresistant to creasing and wilting and is capable of being reshaped attemperatures sufllciently low to prevent in- Jury to the fabric whileretaining its natural resiliency and softness.

13. Composite textile material characterized by crease resistance,increased strength, and ability to retain its shape, comprising a fabriccomposed of interassociated yams respectively formed from differenttypes of fibers of textilemaking length, one of said yarns beingcomposed of fibers of a water-insoluble vinyl resin having an averagemacromolecular weight of at least 7500, said vinyl resin fibers ,beingat least partially heat-fused to said different type of fibers.

14. Composite textile material characterized by crease resistance,increased strength, and ability to retain its shape, comprising a fabriccomposed of one type of yarn intimately associated with another type ofyarn, one of said yarns being composed "of a vinyl resin substantiallyidentical with the product of the conjoint polymerization of a vinylhalide with a vinyl ester of an aliphatic acid, the proportion of vinylhalide to vinyl ester in the polymer and the average macromolecularweight of the polymer being so correlated that vinyl resin fibers formedtherefrom fuse at a temperature sufliciently low to avoid injury to saidother yarn during a heatfusing operation, said polymer having an averagemacromolecular weight of at least 7500, the two types of yarn being atleast partially fused to each other.

15. Composite textile material characterized by crease resistance,increased strength, and ability to retain its shape, comprising a fabriccomposed of one type of yarn intimately associ ated with another type ofyarn, said yarns being at least partially fused to each other, one ofsaid yarns being composed of fibers of a vinyl resin substantiallyidentical with the product resulting from the conjoint polymerization ofa vinyl halide with a vinyl ester of an aliphatic acid and containingbetween about and about 95% by weight of the halide in the polymer, saidresin having an average macromolecular weight of at least 7500, wherebysaid fabric is highly resistant to creasing and wilting and is capableof being reshaped at temperatures sufliciently low to prevent injury tothe fabric while retaining its natural resiliency and softness.

16. Composite textile material characterized by crease resistance, lightresistance, increased from about 42% to about 82%, valeraldehyde.

from about 35% to about 62%, and hexaldehyde from about 33% to about45%; said vinyl resin having an average macromolecular weight of atleast 7500, and being resistant to ultra-violet light and to elevatedtemperatures for long periods of time.

17. Composite textile material composed of at 7 least two differenttypes of fibers of textilemaking length, one of said fibers beingcomposed of a vinyl resin having an average macromolecular weight of atleast 7500, and substantially EDWARD W. RUGELEY. THEOPHH-US A. FEILD,JR. JOHN F. CONLON.

